Designer drug Flakka makes people have sex with trees and is most addictive narcotic known

Bath salts (pictured) have a similar chemical structure to flakka. The primary ingredient in bath salts -- but not flakka -- has been bannedDEA

Scientists in the United States have warned that a new drug, alpha-PVP, or "flakka" - blamed for the bizarre behaviour of users - is as addictive as its "cousin", "bath salts" (MDPV), but with even scarier effects.

Also known as "gravel", flakka, a humble street drug manufactured in China, India and Pakistan and sold for as little as $5 (£3.50) , has only been around for a few years but its popularity - and notoriety - is growing rapidly.

In 2010 no incidents involving flakka (alpha-Pyrrolidinopentiophenone) were recorded by the US Drug Enforcement Agency (DEA), but by 2014 there were 670 related incidents, mostly in Florida but also in other states including Texas and Ohio.

Kenneth Crowder from Orlando was high on flakka when he was arrested for being naked, trying to have sexual relations with a tree, then stabbing a police officer with his own badgeBrevard County Sheriff's Office

However it is the bizarre effect of flakka on its users that are causing concern. In recent incidents a man attempted to have sex with a tree, a girl stripped naked and ran at police naked and covered in blood, and another man impaled his buttocks on a 10-foot fence surrounding a police station.

Users of the drug, which can be snorted, injected, smoked or swallowed, experience rising body temperatures, leading them to strip off their clothes, as well as hallucinating that people are chasing them and trying to kill them.

Now it appears that as well as being seriously mind-bending, flakka is also seriously addictive. In tests conducted on rats, researchers from Scripps Research Institute in La Jolla, California found that rats quickly became dependent.

Rats were recorded as pushing at a lever to obtain their flakka fix with greater regularity, and were soon prepared to push a lever hundreds of times to obtain one dose of the drug. This means flakka is roughly as addictive as bath salts but with additional symptoms including aggression and psychosis.

"Our data show that flakka is as potent as MDPV, making it a very good stimulant, arguably with worse addiction liability than methamphetamine," said Scripps chemist Tobin J. Dickerson in a press release.

The main ingredients in bath salts were banned in 2011. The DEA, which issued a temporary ban on flakka in 2014, now seems likely to ban it outright.